Does algorithmic trading harm liquidity? Evidence from Brazil

Abstract This paper provides the first evidence of algorithmic trading (AT) reducing liquidity in the Brazilian equities market. Our results are contrary to the majority of work which finds a positive relationship between AT and liquidity. Using the adoption of a new data center for the B3 exchange as an exogenous shock, we report evidence that AT increased realized spreads in both firm fixed-effects and vector autoregression estimates for 26 stocks between 2017 and 2018 using high-frequency data. We also provide evidence that AT increases commonality in liquidity, evidencing correlated transactions between automated traders.